Art of separating and apparatus therefor



Jan. 28, 1930. F. R. JOHNSON 1,744,967

ART OF SEPARATING ANDAPPARATUS THEREFOR Filed Aug 25, 1927 2 Sheets-Shee1 I I I I I I I O I 1' 15 i 5 13 F l I V 1 U6 77 to? /7 I .Fedfi.Joiwwon 1-9 fl'l%07 71ey6' Jan. 28, 1930. F. R. JOHNSON 1,744,967

ART OF SEPARATING AND APPARATUS THEREFOR Filed Aug. 25, 192"! 2Sheets-Sheet 2 Patented 28 1930 UNITED STATES FRED ROTHWELL OHNSON, OFHAMBURG, NEW YORK ART OF SEPARAT1NG AND APPARATUS THEREFOR Applicationfiled August 25, 1927. Serial No. 215,468.

This invention relates to improvements in ,the art of- Separation ofunlike particles found mixed in a mass. More particularly the inventionprovides a 5 method, and apparatus for practicing it, which willprobably be found applicable most frequently in cases where theparticles to be separated differ in shape, some for example, vbeingsmall or flat, while others to be separated from them are larger or of ashape more adapted forrolling. Ordinarily this will'attend a differenceof material, as for separating garnets from mica in a comminuted masscontaining both. But theutility isnot limited to that, but may beapplied for separating difi'eren't shapes of the same,

material, assfor separating the round particles from the slivers in aground mass of artificial abrasives. And it is applicable also in caseswhere the distinction between particles to be separated may not lie intheir shapes, so much as in their respective abilities to acquire acharge of static electricity.

The method by which the separating is accomplished subjects all of theparticles to a test by'a continuous process in the course of which eacharticle is deposited on an inclined surface set at a suitable angle sothat, for example, the fiattish particles will 'not 39 slide down itwhile the rounder bodies will do so. In the instance mentioned the flatparticles hold their position by friction; and preferably .they arecontinuously removed from the place of deposit as by providing that thesaid incline on which they are deposited is a conveyor belt movingupward which carries them up and discharges them from its top. The powerof the belt, to hold the smaller or flatter particles and not the largeror rounder ones, may be enhanced by making the belt corrugated; and theforce offriction, or the force akin to friction, with which the beltholds certain of the particles may be r amplified by charging all of theparticles pre- 0 liminarily, or subjecting them to an equal opportunityof becoming charged, with electricity, and providing an electrode ofopposite sign close under the belt at the place where the are depositedthereon, so that those whic are equally charged and are lighter, or havebecause of their shape or theirv material acquired stronger charges thanothers, or carry their charges closer to the belt, are held morestrongly on the belt. A further separation may be effected, as a part ofthe same continuous process, among those particles which have been drawnoff from the place of deposit by gravity and have rolled down the belt.An electrode charged with static electricity of suitable polarity withreference to the polarity with which the falling particles are chargedmay be set near the course through which they are falling so as to defflect the trajectory of those which are the more strongly charged, sothat they fall in a place where they are by themselves, apart from theplace Where the less strongly charged particles fall. For one example ofa practical application of this the process may be considered as it maybe applied for-the 7o purification of crushed kauri gum. All of y thecomminuted materials being fed in a thin stream over a plate having astrong negative electro-static charge, each particle thereby picks-upsome negative charge, so that when the stream falls upon abelt movingupward at an angle, close above a strongly charged positive electrode,the sticks, leaves and small dirt, lying fiat upon the belt and furtherheld by the electric attraction, are carried upward by the belt, whilethe gum and mud balls roll down the incline of the belt. But, as theyfall from its bottom and pass near another electrode positively charged,thesefalling particles are difi'erently affected, the mud alls beingdrawn toward the electrostatic positive pole, while the gum (which hasless good conducting power and therefore has picked up on the surfaceless of negative electricity from its passage over the negativelycharged plate) is not drawn so much toward 'the positive electrode andtherefore falls more nearly in its. natural trajectory. If thepercentage of impu'rities thus separated from the gum is not suflicient,or if too much gum is carried away with either of the separated classes,the product may becarried to a higher degree of perfection by passing itimmediately and automatically through apparatus arranged in tandem toreceive the productvof' 10 either of the classes and adjusted to thepari represents the apparatus of the invent-ion;

ticular needs of the material which it is to handle. It will be observedthat the method does not require in all instances that the inclinedsurface be one which is moving upward as a conveyor, for with certainmaterials a distinction may exist as to the places where the two classesof material fall from the incline; as :Where all materials fall but someis held back by friction as it slides down so as to fall more nearlyvertical, While other material of rounder shape Bounding down theincline falls further away.

The invention may be applied in various Ways", one of which isillustrated and described herein with apparatus. for practicing it, asan example, to which however the invention is not limited. It isintended that the patent shall cover, by suit'able expression in theappended claims, whatever features of patentable novelty exist in theinvention disclosed.

In'the accompanying drawings:

Figure 1 is an elevation of apparatus, in section, in which the art ofthe invention is being racticed and is embodied, the appa ratusillustrated in Figure 1 being a detail on a larger scale of part of thatshown in Figures 2 and 3; and

Figure 2 is a side elevationof apparatus for practicing the invention asa process and and Figure 3 is an elevation of the same in section on theline 33 of Figure 2.

Referring to the drawings, 10 indicates a frame holding variousinstruments in vertlcal succession from the hopper 12 downward, forvdealing with all or part of the ma.-

'under the belt.

terial a b c seen in the hopper 12, which has an open bottom fordelivery of the material at a rate determined by the setting of thescrew 13, by which one side wall 14 of the hopper can be raised a littleabove the roll 16, which, turning at a suitable rate, contin uouslycarries material out from the bottom of hopper 12 under the gate 14, sothat it falls upon an apron 17 which is of metal steep'enough for thematerial to slide down by gravity and is strongly charged with staticelectricity of a certain polarity, for

example, negative. The bottom edge of this' blade is serrated,preferably having points 18,- seen in Figure 3, and can be ad usted to asuitable elevation and there held by the clamp 19, Fig. 4, so that itspoints are close above the surface of the conveyor belt 20,:

leaving room for material on the belt to pass under them, and are alsonear the elec-.

trode 30 of oppositeolarity which is close This It 20 may preferably beof rubber, which is a convenient flexible insulating substance, and formany materials may preferably be corrugated so as to make it morediflicult for parts of the mass to slide down the belt while notpreventing larger or differently shaped articles from sliding or rollingdown it. This belt is represented as being carried on guide rolls 22,24, by which it'is driven so that its upper surface moves upward, and isheld taut to, a suitable ment of the bearing 25 of the roll 24, by thedegree, this latter being affected by adjustscrew 27 and by the clamp26. The'latter 32 crossing between two arms 34, one at each a edge ofthe machine, which areadjustable and holdable by the pin and slotclamping arrangement 36, the tube itself being held by screws 38fastened to the insulating block 32. Another'electrode, of positivepolarity, is represented at 40 where it is set near the trajectory ofarticles which fall from the bottom of the belt. The connection to thesevarious electrodes may be made in any ordinary or suitable manner, andthe static charge may be of any suitable voltage. It has been found thatfrom 5000 to 35,000 volts as produced by adisk static machine issuitable, although it should not be understood that the practice of theinvention is limited to this range. The lower edge of the apron 17 maywith advantage be adjusted to be within a half inch or less of thepositive electrode 30 which is beyond the belt 20 from it, with the belt20 and material thereon intervening. The dimensions and the speed of thebelt may vary according to circumstances,

one suitable dimension for example being anywhere between one foot andfour feet wide for the belt, moving at a speed of ten to fift feet perminute.

In t e operation of this apparatus, practicing the process of theinvention, the mixed I a material a b 0 passes out from the hopper 12 ina continuous. thin. stream, determined by the setting of the gate'14,passing out with the rotation of the roll 16, which may conveniently bemerely a length of three inch shafting or other material suitablymounted in bearings at its end; and this thin stream of the mixedmaterial flows down over the apron 17 and: slides off the points 18,with each particle be-.

the small particles to roll down, even t'fiiiugh they be round, andthese are held thus by a force which is akin to friction so far as thepurposes of the present invention'are concerned, so that in the claimsthe word friction is used broadly as typifying pure friction and alsoforces akin to friction, among which may also be classified the holdingtightly upon the belt, with the effect of preventing sliding, whichresults from the action of the'electrostatic forces. Material 0 which iscarried upon the belt would be the sticks and leaves and fine dirt inthe kauri gum illustration cited, which had acquired a charge ofnegative electricity and so is marked 0, and which is delivered by theconveyor upon a chute 44, to

- be gathered in some convenient place as tail in The particles (1' andb which gravity 'pu ls down on the belt are discharged as indicated inFi re 1 and fall freely from the bottom of the elt. They may, however,be separated automatically into those which being rounder are travellingdown the incline with greater velocity than the rest and thus fallfurther from the belt, indicated at b, and those which fall morestraight indicated at a.

In the illustration mentioned it is assumed that the mud balls would bethe more round and would fall farther from the belt, and they wouldconstitute middlings I), while the purest gum particles a would fallmore directly. Figure 1 illustrates also the use of another positiveelectrode 40 which being placed near the falling stream pulls morestrongly on the mud balls than on the gum balls because they have beencapable of picking up a large charge of electricity in passing over theapron 17, and this pull accentuates the separation between the two kinds(1 and b, so that a deflector 42 can guide each kind to a place byitself. Figure 2 illustrates how the process can be repeated in the sameapparatus for the further separation of one of these separated streams,the apparatus being set in this instance to operate upon a streamfalling in the position of the stream a of Figure 1,

which the deflector board 42 throws upon a lower apron 17 passing itthrough apparatus similar to that above it, already described, andarranged to deposite its tailings, middlings and concentraterespectively in the containers 45, 43 and 41;

7 Thus theconjoint application of the forces of' gravity and of frictionto the particles of the mixed mass; when arranged so that they are freeto respond independently according to their several characters, resultsin gravity controlling theultimate location'of some of them and frictionthe ultimate location of others, these two locations being at 'cabledistances 2. art for effecting the esired separation of di erent classesof particles that were in the mixed mass.

The desired polarity of apron 17 and opposite polarity of the insulatedelectrodes 30 and racti- 'asre 17 increase the effect of electrode 30 tohold fiat particles on the belt, as the points create a spray whichrepels while a more flat surface .will attract. ,The rubber belt is aninsulator 'which tends to prevent the electricity from arcing acrossbetween the charged electrodes. Other suitable insulating material suchas leather or canvas can be used.

I claim as my invention r 1. A process for separation of diverse classesof particles in a mass of freely movable particles wherein the classesare mixed, comprising the conjoint application to each particle of theforce of gravity, a force exerted by an underlying solid bodyobstructing the direct pull of gravity, an electric force, and africtional pull; wherein'the force of gravity is applied to the particledownward; the obstructing force is applied to obstruct a direct downwardwhile permitting a laterally downward movement of the particle; thefricpositely lateral, friction being-generated by v the said downwardpull of gravity; and the electric force is applied to increase thepressure and'friction of the particle against the said underlying body,whereupon the particle moves laterally downward or upward according tothe resultant of said forces actinguonit.

2. eparatingapparatus comprismg a conveyor having a material-engagingsurface set to move upward at an incline; means for ex posing the mixedmaterial to become charged with electricity; means for spreading thecharged material on said surface; andan electrode, ofpolarity oppositeto that of the.

material, close under the said surface and arranged to force eachparticle of said mate-' rial toward that surface; the said incline beingslight enough for the conveyor to held against gravity one class ofparticles Wh1Cll is in the mixed material and being too great for theconveyor to hold against gravity the other class therein. I

3. Separating apparatus 'comprlsing a hopper for material havingmeansfor the gradual discharge thereof; an electrically charged apronover which the discharged material flows and whereon 1t is'exposed tobecoming charged with electricity; 'a conveyer upon which the aprondelivers it-,-'set to move upward at an incline; and electrical meansfor drawing the chargedumaterial against the conveyer with increasedfrictlon thereon, whereby" the distinction between partlcles ofdifferent classes in the material-is enhanced ards their respectiveadhesion to or falling a ongthe inclined conveyer.

'4. Separating apparatus comprising a hopper for mixed material withmeans for the gradual discharge of material from the hopper; an apronover which the discharged material flows; a conveyer to which the apron5 discharges the material, having a materialengaging surface set to moveupward at an incline; an electrode set under the conveyer close to theplace where material is deposited thereon; the said apron being chargedelectrically of opposite polarity and having at its delivery edge pointstoward said electrode and at a short distance therefrom; whereby theelectrical action draws particles more strongly toward the surface ofsaid conveyer, e

with friction enhanced, distinctively according to the class of eachparticle in the mixed material; particles of one class being heldagainst gravity on the conveyer, while the urge of gravity .issuflicient to overcome the friction of the other class on the conveyer.

5. Apparatus for separating comminuted material into classes comprisingan inclined surface on which one class of the material I can be moveddownward by gravity and on which the tendency of gravity to draw theother class of material downward is re- 7 strained to a greater degreethan in the case of the first material by the engagement of therestrained material with the surface of the incline, yet notsufficiently to prevent the second class also from moving'down theincline; means for charging the material electrically before it leavesthe incline; and an electrode set near the trajectory of one of saidclasses of material leaving the incline whereby its course is deflectedto increase the separation between the two classes of falling material.v

6. A separator for diverse classes of parti- 4o cles in mixed materialcomprising a hopper for holding the mixed material having at its bottoma roll for holding the material therein and for feedin it thence under abottom of a side wall 0 the hopper; an electrically charged apron uponwhich said roll delivers the material; a belt conveyer set to moveupward at an incline, receiving the'discharge from the apron; the said rincline being such that one class of the mixed material is heldfrictionally thereon and moves upward therewith while another class isdrawn by gravity more powerfully than it is held by friction "and movesdown the upward moving belt; and an electrode of opposite polarity fromthe apron and the material, set under the belt where the material isreceived from the apron and adapted to draw particles of the mixedmaterial more tightly against the surface of the conveyer, wherebydistinctions as to fric; 6 tional adhesion or non-adhesion of differentclasses of particles to the belt are increased. Signed alt-Hamburg,Eriecounty, N; Y., this 13th day of August; 1927.

u FBEDABOTHWELL JOHNSON.

